feat(@embark/test-runner): make evmMethod globally available + docs

packages/stack/test-runner/src/lib/index.js

@@ -177,6 +177,8 @@ class TestRunner {
       }
     };
 
+    global.evmMethod = this.evmMethod.bind(this);
+
     global.getEvmVersion = async () => {
       return this.evmMethod('web3_clientVersion');
     };
@@ -382,6 +384,9 @@ class TestRunner {
         if (error) {
           return reject(error);
         }
+        if (res.error) {
+          return reject(new Error(res.error));
+        }
         resolve(res.result);
       }
     );

site/source/docs/contracts_testing.md

@@ -293,7 +293,7 @@ This function lets you increase the time of the EVM. It is useful in the case wh
 await increaseTime(amount);
 ```
 
-`amount`: [Number] Number of seconds to increase
+- `amount`: [Number] Number of seconds to increase
 
 ```javascript
 it("should have expired after increasing time", async function () {
@@ -325,6 +325,26 @@ await getEvmVersion();
 
 Returns a string, eg: `EthereumJS TestRPC/v2.9.2/ethereum-js`
 
+### evmMethod
+
+If there are EVM methods that are not supported by the web3 library you use, Embark exposes the global function `evmMethod` that lets you call the RPC method directly.
+
+#### Syntax
+`evmMethod(rpcMethodName, parameters)`
+
+ - `rpcMethodName`: [string] Name of the RPC method to call.
+ - `parameters`: [Array<any>] Optional array of parameters, as specified by the RPC method API.
+
+#### Usage
+For example, let's say you are using `web3.js` in your tests, but would like to call the `eth_signTypedData` RPC method. Because `web3.js` does not support this method, it won't be possible to use `web3.js` for this call. Instead, we can call the `eth_signTypedData` RPC method in our tests using the global `evmMethod` function:
+
+```javascript
+ const signature = await evmMethod("eth_signTypedData", [
+  accounts[0],
+  data
+]);
+```
+
 ## Code coverage
 
 Embark allows you to generate a coverage report for your Solidity Smart Contracts by passing the `--coverage` option on the `embark test` command.